In order to measure a blood sugar level of the patient with diabetes, it is required to take a sample of the blood from the patient. Various kinds of pricking devices have been proposed for sampling a small amount of the blood. The pricking device for sampling the blood is generally composed of a lancet and an injector (see Patent Document listed below). The lancet serves to actually prick the patient. While on the other hand, the injector has a function of launching the lancet toward a predetermined region (e.g., finger tip) of the patient.
Specifically, the lancet has a pricking needle, whereas the injector has a plunger equipped with a lancet-attachment portion and a spring. The spring of the plunger is used in its compressed state. The releasing of the compressed spring can give a quick movement of the plunger to launch the lancet for the pricking. For use of the pricking device, the lancet is attached to the plunger of the injector, and the compressed state of the spring is released by an actuating of a trigger of the injector. Such releasing enables the compressed spring to be expanded so that the plunger with the lancet attached thereto is launched toward the subject of the blood sampling. As a result, the predetermined region in the subject of the blood sampling is pricked by the lancet attached to the plunger.